The machines of the type indicated are utilized to engrave signs and/or characters of different type on surfaces of pieces of metal, of plastic material, etc., the whole set of signs and characters engraved comprising a key or identification reference or a supplier of determined information.
Thus, for example, in the automobile industry nearly all of the parts utilized carry engraved reference numbers. It is necessary that the frame and motor of the vehicles carry an identifying number imprinted on them.
In order to carry out this engraving, it is necessary that the striker point, besides its axial placement originating from the engraving device, can be displaced according to two axes perpendicular to each other, parallel to the surface to be engraved. In order to meet these requirements machines are known which have two sides which displace each other in perpendicular directions, activated by the corresponding motors. Machines of this type have the drawback that they occupy a relatively large volume, due to the existence of the two movable slides.
For the purpose of reducing the volume of the machine, machines are known in which the engraving device is mounted on a support which can be moved in controlled manner along an axis parallel to the surface to be engraved and also can turn in both directions a certain angle, also in a controlled fashion, around said axis. This type of machine is usable when the surface to be engraved does not require an excessive turn of the striking point, in such a way that its incidence on the surface to be engraved is practically normal in all cases.
Machines of this type are described, for example, in German patent No. 24 23 424 and in European patent No. 371,896.
In German patent No. 24 23 424, the axis over which the support of the striking device is mounted is comprised of an endless screw which crosses a threaded bore hole of the support. This endless screw will cause the linear displacement of the support toward one side or the other. Also, on the lead screw there is mounted a U shaped stirrup, the central branch of which is related to the support and with the activating motor through the gear systems. The tipping of the stirrup causes the turning one way or the other of the support, around the lead screw.
This configuration involves a considerable complication of the activating mechanisms, due partly to the arrangement of the two activating motors on the chassis of the machine. However, the turn of the support around the endless screw provokes a certain linear displacement thereof, even though of minimal magnitude, which acts to the detriment of precision in the engraving operation.
In the European patent No. 371,896, the axis on which the support of the engraving device is mounted consists of a bar of circular section, along which the support can be moved and on which it can turn a certain angle in both directions. As in the previous case, when the two activating motors located on the chassis of the machine operate, transmission mechanisms are required from the two motors for the linear displacement and for the turn of the support, complicating the construction and function of the whole.
In the two cases commented upon, the support of the engraving device is revolving with respect to the lead screw or bar along which the linear displacement of the device takes place.